There has been a marked increase in the virtualization of the computation, networking, and storage components of data centers. Particularly, virtualization of a server, which is used as a computing resource in data centers, is one of the most developed and core techniques in cloud computing. In a server virtualization technique, multiple virtual machines may be virtualized from a single physical server. In addition, independent operating systems and applications may be installed in the physical server for each of the virtual machines. As such, the utilization rate and the hardware resources of the physical server may be effectively increased.